spread tail

spread tail (plural spread tails)

1. The tail of a bird (or likeness thereof) when the tailfeathers are held tautly outward in a fan-like arrangement.
   • 1893, Charles Frederick Marvin, Anemometry, page 16:

     Moreover, for slight deflections of the vane from the wind direction a spread tail presents a greater extent of surface to the wind than a straight-tail vane of the same dimensions.

   • 1901 June, “The Brahma Fowl”, in American Poultry Journal, volume 32, number 6, page 497:

     Now, as we understand all this the Brahma tail most admired is the full spread tail that almost forms a half circle to build out the saddle and make it possible for the saddle to make the concave sweep to the coverts.

   • 1964, G. J. Broekhuysen, “A Description and Discussion of Threat- and Anxiety-Behaviour of Burhinus Capensis (Lichtenstein) During Incubation”, in Feestbundel H. Boschma, page 244:

     There is evidence which seems to show that a spread tail is more aggressive than a folded one and that cocking the tail up is more aggressive than pointing the tail downwards.

   • 2012, Ulla M. Norberg, Vertebrate Flight, page 236:

     Birds with long forked tails, such as some swifts, swallows, terns, frigate birds, and the fork-tailed falcon (Elanoides furcatus), use the spread tail as a long flap on each side to help deflect air over the main wing surface and keep the flow attached at higher angles of attack than otherwise would be possible.